Variable inductance unit



May 10 1927.

M. M. EELLS VARIABLE INDUCTANCE UNIT Filed Sept. 20, 1926 -:Ni/Ton Meir-win [055 Patented May 10, 1927. r

UNITED STATES PATENT OFFICE.

MILTON MERWIN EELLS, OF CHICAGO, ILLINOIS, ASSIGNOR TO WESTERN COIL 8t ELECTRICAL (10., OF RACINE, WISCONSIN.

VARIABLE INDUG'IANCE UNIT.

Application filed September 20, 1928. Serial No. 126,627.

This invention relates to a variable inductance unit or, in other words, to variably in ductively coupled coils, particularly adapted for radio work.

Objects of this invention are to provide a novel. form of inductively coupled coils which may be more compactly constructed and more simply made than those heretofore known, and in which the coils themselves may be made smaller than the usual practice would Warrant.

Further objects are to provide two coils so associated that they may be caused to add in their electromagnetic effect, or may be caused to buck each other without posi tioning one coil within the other, as has been the usual practice heretofore, and without requiring an excessive spacing of the coils laterally with respect to their planes An embodiment of the invention shown in the accompanying drawings in which:

Figure l is a fragmentary view of av radio set showing the mounting of the coils and showing them in one position of adjustment;

Figure 2 is a sectional view approximately on the line 2 2 of Figure 1, such view showing primarily the coils themselves;

Figure 3 is a detail view of the shaft for the .mov'able coil;

Figure 4 is a View of the end of the spring associated with such shaft.

Referring to the drawin s, it will be seen that the front panel or p ate 1 of a radio cabinet has been indicated. This plate is provided with an aperture through which a threaded sleeve 2 projects. This sleeve is locked in place by means of nuts 3 and e on opposite sides of the panel 1. It is to be noted that the nut 4 clamps one end of the U-shaped spring 5 rigidly in place.

Vithin this sleeve a shaft 6 is positioned, and is provided with a pin 7 which contacts with a projecting portion 8 of the sleeve 2 and thus limits the rotary motion of the shaft.

The shaft 6 is provided with a groove 9 (see Figure 3) within which the forked or cut-away portion 10 of the spring 5 fits. This spring presses the shaft downwardly. The shaft, however, is held from slipping from the sleeve 2 by means of the adjusting knob or manipulating knob 11 positioned on the outer side of the panel 1. This knob receives the upper end of the shaft which is locked thereto by means of a set 12 in the usual manner. Preferai' ly, the knob is hushed and bears against the outer face of the outer nut 3. Thus the shaft is positively positioned in its correct p ace at all times, andv a sufficient amount of friction is given to such shaft by means of the spring so as to hold it in any position of adjustment and yet permit ready adjustment of such shaft.

The coils may be made in any suitable design. It has been found that a spider web coil or a flat cries-cross winding spiral, such as indicated in the drawing, eminently sat isfactory.

The movable coil 13 is tangentially mount ed upon the inner end of the shaft '6, as shown in Figure 2, and the stationary coil 14: is mounted in a plane paralleling the axis of the sh ft ('3 The axis of the coil 14-. preferably Jasses at right angles through the axis of the shaft 6, as is apparent from Fig ure 2. The stationary coil 14: may be held in any suitable manner, as upon an insulating central block '15 (see Figure 1).. such block being in turn held by an arm '16 secured to the panel 1, thus providing a very simple mounting for the coil.

It is to be particularly noted that the lines of force which encircle the winiflinc'. of the coil lei may pass through the moi able coil 13 in either direction, so that the clifect of the coils may be varied from an additive effect to a bucking or opposing effect. Further, it is to be noted that the lines of force pas-s approximately at right angles through the plane of the movable coil 13 when it is in either extreme position, and thus the maximum effect may be secured. Obviously, when the movable coil stands at right angles to the stationary coil, its effect is zero, such position being indicated in dotted lines in Figure 1.

It will be seen by this invention that it is not necessary to mount the movable coil within the stationary coil, as has heretofore been considered necessary, nor is it necessary to space the movable coil a great distance from the stationary coil and rotate it about a diameter, as has also been the practice heretofore.

It will be seen that relatively small coils may be employed and a relatively simple construction resorted to in the practice of this invention, and further it will be seen that the electrical effect is in no way sacrificed by this manner of mounting and relating the coils. If anything, the capacity effect of the coils is decreased. Further, it will be seen that the construction may be simply followed and readily produced by ordinary manufacturing methods.

Although the invention has been described in considerable detail, such description is intended as illustrative rather than limiting as the invention may be variously embodied and as the scope of such invention is to be determined as claimed.

I claim:

1. The combination of a panel, a stationary coil supported therefrom, a shaft mounted approximately parallel to the plane of the stationary coil and at right angles to the axis thereof, a support for said shaft, means for rotating said shaft, and a movable coil mounted tangentially with reference to said shaft, whereby said movable coil may be rocked approximately about a tangent and may thus vary its effect on the stationary coil.

2. An inductance apparatus for radio sets comprising a supporting panel, a stationary coil supported therefrom, a sleeve carried by said panel, a shaft mounted Within said sleeve, means for operating said shaft mounted on the outer side of said panel, and a movable coil carried by said shaft and located on the inner side of said panel and positioned in proximity to said stationary coil, said shaft being approximately tangent to said movable coil.

3. An inductance apparatus for radio sets comprising a supporting panel, a stationary coil supported therefrom, a sleeve carried by said panel, a shaft mounted Within said sleeve, means for operating said shaft mounted on the outer side of said panel, and a movable coil carried by said shaft and 10- a shaft tangent to the movable coil and secured thereto, said shaft having a groove therein, a sleeve furnishing a bearing for said shaft and having a projecting portion forming shoulders, a pin carried by said shaft and adapted to contact with said shoulders to limit the rocking motion of said shaft, a binding spring engaging with in said groove and locked with reference to said sleeve, and a manipulating member secured to said shaft.

A radio apparatus comprising a panel, a sleeve passing through said panel, means carried by said sleeve and positioned on opposite sides of said panel for locking said sleeve in place. A manipulating member secured to said shaft and bearing against the outer locking means, said shaft having a groove therein, a U-shaped spring having one end held stationary with reference to said sleeve and having its other end forked and fitting Within said groove, a movable coil tangentially mounted with reference to said shaft and secured thereto, a stationary coil, and means for holding said stationary coil in proximity to said movable coil with the shaft intersecting the axis of the stationary coil.

In testimony that I claim the foregoing I have hereunto set my hand at Racine, in the county of Racine and State of Wiscon- MILTON MERIVIN BELLS. 

